San Mateo County, CA Zoning Overlays & Bonuses: Density Bonus Law (2026)
Key Facts
- Maximum density bonus
- 35% (80% for 100% affordable projects)
- Very low income entry threshold
- 5% of units for a 20% bonus
- Low income entry threshold
- 10% of units for a 20% bonus
- Concessions/incentives granted
- 1 to 4, scaled to affordability level
- Parking cap
- 1 space (studio/1BR) to 2.5 spaces (4+BR)
- Rental compliance term
- Minimum 55 years, deed-recorded
- Geographic scope
- Unincorporated county only, excludes rural Coastal Zone
Summary
Unincorporated San Mateo County grants residential developers a density bonus of up to 35 percent above the zoned maximum, plus incentives, parking reductions, or waivers, when a project sets aside qualifying units for very low, low, or moderate income households under Zoning Regulations Chapter 8.436. The bonus applies only outside the incorporated cities and excludes the rural Coastal Zone, which follows a separate Local Coastal Program density bonus policy.
To be eligible for a density bonus and other concessions, incentives, and waivers pursuant to this Chapter, a project must provide the required amount of qualifying housing units, as described in Section 8.436.050. The project must also: (1) meet the definition of "residential development" contained in Section 6440.2.13; (2) meet all requirements and standards of the Zoning Regulations, prior to the calculation of any additional density pursuant to the density bonus, and prior to any granted concessions, incentives, or waivers; and (3) be located within unincorporated San Mateo County, with the exception of the rural area of the Coastal Zone, as defined in the County's Local Coastal Program. Projects located within the rural area of the Coastal Zone are not eligible for a density bonus pursuant to this Chapter.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 47).
Full Breakdown
) locally. A residential development of five or more parcels or units qualifies for a density bonus stacked on top of the maximum net density otherwise allowed by the zoning district or General Plan land use designation. 5 points for each additional 1 percent, capped at 35 percent once 11 percent of units qualify. 5 points per additional 1 percent to the same 35 percent cap at 20 percent. For-sale common interest projects can instead use a moderate income tier (10 percent minimum for a 5 percent bonus, capped at 35 percent at 40 percent).
A project that is 100 percent income-restricted, with no more than 20 percent moderate income units, receives an 80 percent bonus, and a 100 percent senior citizen or senior mobile-home project receives 20 percent regardless of income mix. 5 space per bedroom or per unit near a major transit stop. 110, with no separate discretionary hearing required. 24.
Violations & Fines
Chapter 8.436 does not fine developers; it enforces compliance through recorded restrictions. Grant deeds for ownership qualifying units must incorporate a declaration of restrictions assigning the County all of the seller's rights to enforce resale controls, and the County Housing Department monitors resales to prevent abuse or violation of those controls (Section 8.436.100(3)(c)(3)). Rental qualifying-unit agreements are recorded as deed restrictions binding for at least 55 years regardless of any change in ownership, and the County enforces the recorded agreement against noncompliant owners (Section 8.436.100(4)(c)).
Frequently Asked Questions
Does this density bonus apply inside Redwood City or San Mateo?
Do I need a discretionary hearing to get the density bonus?
What if my parcel is in the Coastal Zone?
How long must the affordable units stay affordable?
Sources & Official References
Other rules in San Mateo County
California rules heatmap·Compare San Mateo County to another location·View the California zoning overlays & bonuses overview
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